Field of the Invention
The present invention relates to an observation optical system and an observation apparatus including the same, and the observation optical system is suitable for use as an observation optical system of observation apparatus, such as binoculars and telescopes having a function (image stabilization) of optically correcting image blur caused by shaking, for example.
Description of the Related Art
In observation of targets (objects) with observation optical systems of observation apparatus, such as binoculars and telescopes, as a magnification (observation magnification) of the observation optical system becomes higher, stronger image blur is caused by shaking. Hitherto, as observation optical systems to be used for observation apparatus, there have been known observation optical systems employing image stabilization in order to reduce image blur caused by shaking. In many types of observation optical systems, an object image formed by an objective lens is inverted to an erect image by an image inverting unit, and this erect image is observed through an ocular lens in an enlarged manner.
In Japanese Patent Application Laid-Open No. H11-194262, there is described an objective lens including a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. As an image blur correcting system, at least one of the second lens unit and the third lens unit is configured to move in a direction perpendicular to an optical axis for image blur correction. In Japanese Patent Application Laid-Open No. H11-258518, there is disclosed an objective lens including a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. As an image blur correcting system, at least one lens unit forming the objective lens is configured to move in a direction perpendicular to an optical axis for image blur correction.
In general, observation optical systems having image stabilization are demanded to accurately perform image blur correction with a small aberration variation during image blur correction. In order to satisfy those demands, it is important to appropriately set, for example, the lens configurations of an objective lens and an image stabilizing lens unit for image blur correction, which form an observation optical system.